Hammer mill

ABSTRACT

The rotatable hammer assembly is enveloped by a screen assembly of screen elements held in position by screen retaining members having abutting ends hingedly joined, the other ends provided with manually operable latch means to secure the screen assembly in place about the hammer assembly.

United States Patent [1 1 Helms l HAMMER MILL [76] Inventor: Robert D. Helms, 73-845 Flagstone Ln., Palm Desert, Calif. 92260 [22] Filed: July 16, 1973 [2l] Appl. No.: 379,581

[52] US. Cl 241/73; 241/l86.l [51] Int. Cl. B02c 13/284 [58] Field of Search 24l/73, 74, 185 R, 186 R, 241/186.1

[56] References Cited UNITED STATES PATENTS 2,557,865 6/l95l Emmanouilidis 241/74 July 8,1975

6/1953 Jacobson 24l/l86 R 3,079,095

2/1963 Beards Primary Examiner-Roy Lake Assistant Examiner-E. F. Desmond Attorney, Agent, or Firm-Boniard l. Brown [57] ABSTRACT The rotatable hammer assembly is enveloped by a screen assembly of screen elements held in position by screen retaining members having abutting ends hingedly joined, the other ends provided with manually operable latch means to secure the screen assembly in place about the hammer assembly.

4 Claims, 4 Drawing Figures WW-mm. 8 1915 FIG. 4.

SHEET 2 BF 2 HAMMER MILL BACKGROUND OF THE INVENTION In the art of comminuting coarse material to fine, appropriately known as fines, the hammer mill is extensively and universally utilized because of its minimum; of moving elements as well as relative simplicity and small number of wearing parts. In its simplest form the mill comprises a rotatable hammer assembly enveloped by a stationary annular screen, coupled with a hopper means for feeding the coarse material into the interior of the screen. The rotating hammer elements of the assembly then impact the material through the perforations of the screen, causing the material to be comminuted.

Aside from considerations ofthe nature of the particular material being comminuted and the degree to which it is to be reduced or fined, it is apparent that the rate of comminuting will depend upon the rate of im paction which, in turn depends on the screen area subject to impaction of the material by the hammer elements. The principal limitation of screen area is that which is imposed by the maximum size hammer assembly which can be sustained by the journal or bearing arrangement which supports the shaft which rotates the hammer assembly.

A concurrent problem is that of replacement or other maintenance procedures directed to the screen element since it is subject to abrasion by the material in the comminuting operation. To a material extent the wear on the screens is uneven due to the direction of rotation of the hammer assembly and to some extent the wear is due to the action of gravity on the flailing hammers and on the material being comminuted. Hence it has been necessary to make provision in the overall design of the mill for rapid maintenance procedures on the screens, including quick replacement in order to reduce the down time of the mill to a minimum.

This design consideration has dictated compromise in a known prior art machine. In order to provide for the rapid maintenance it has been necessary in the prior art mills to design the hammer assembly as an overhung arrangement on a cantilevered shaft supported on one side only of the mill in a single bearing or journal in order to effect screen removal without dismantling a second bearing element. An arrangement of this type is shown and described in my prior art US. Pat. No. 3,169,71 l, for ROTARY GRINDING MILL, issued Feb. 16, I965.

The structure shown and described in that patent, while being a distinct improvement over hammer mills of the art current at that time, imposed a limitation on the size of the hammer assembly which could be overhung on a shaft cantilevered on a single bearing. This imposed a limitation on the axial length of the comminuting screen.

SUMMARY OF THE INVENTION The present invention removes the limitations imposed by a cantilevered shaft and hammer assembly, and provides a new and novel screen retaining assembly which permits the removal of the annular screen from around a rotatable hammer assembly disposed on a shaft between bearing or journal supports on each side thereof.

It is a general object to provide a hammer mill as aforesaid. It is a further general object to provide a screen assembly for a hammer mill having a plurality of generally arcuately configured screen retaining members hingedly coupled together with one end of one of the members being adapted to releasable securement adjacent one end of another of the members, wherefor the screen assembly may be opened thereat by swinging the said one and another members apart by relative movement at this hinge coupling.

It is a particular object to provide the screen assembly with push-pull type toggle clamps for latching the said one and another members at their said ends.

It is yet another object to provide a screen assembly as aforesaid, having substantially identically sized and configured screen elements arranged for assembly and securement by the retaining members.

Having regard with the foregoing summary there will now be disclosed a preferred embodiment of the invention, it being understood that the invention may take other forms than that to be disclosed in the description when taken with the drawings, wherein:

FIG. 1 is a side elevation view of one embodiment of the invention;

FIG. 2 is a right end elevation view of the embodiment depicted in FIG. 1;

FIG. 3 is a left end elevation view, partly in crosssection, taken on line 3-3 of FIG. 1; and

FIG. 4 is a side elevation view in cross-section, taken on the line 44 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 of the drawings there is shown a hammer mill I0 mounted on a base 12. Forming a part of the mill 10 are spaced apart bearings 14 and 16 upstanding from the base I2, forming journals for a power input shaft 18 of the mill 10. An electric motor 20 mounted on the base 12 is coupled to the shaft I8 by means of a flexible coupling 22.

The mill 10 comprises a housing structure 24 formed preferably of sheet metal and defining a hopper inlet 26 for the introduction of material. As seen in FIG. I, the hopper 26 merges into divided passageway duct members 28 and 30 which serve to divide and feed the material into both ends of the comminuting mechanism described below. Hinged door members 32 and 34 form a part of the duct members 28 and 30, respectively, on their lower ends, the doors 32 and 34 being provided with magnets 36 and 38, respectively, secured thereon to extract and retain ferro-metallic particles entrained in the material fed through the duct members.

The housing structure 24 further comprises end wall members 40 and 42, best seen in FIG. 4, which define respective passageways 44 and 46 therethrough and also through respective end plate members 48 and 50 fixedly secured to the end wall members 40 and 42 which are secured on the base 12. As best seen also in FIG. 4, the door members 32 and 34 are secured by hinges 52 and 54, respectively, to the end wall members 40 and 42. Manual latches 56 and 58 are provided to retain the doors 32 and 34 in closed position. By releasing the latches 56 and 58 the doors 32 and 34 may be opened for the removal of any ferro-metallic debris collected and held by the magnets 36 and 38.

As is now seen, the structure 24 defines a passageway for material entering the hopper 26 in coarse condition 1nd exhausting from an outlet 60 at the base of the .tructure, the passageway being defined by the hopper nlet 26, the duct members 28 and 30, the passageways l4 and 46, and the end wall members 40 and 42 to- ;ether with side wall members 62 and 64 whose side :dges are dispersed adjacent the side edges of the end vall members 40 and 42. The side wall members 62 .nd 64 include swingable wall elements 66 and 68, repectively, mounted by hinges 70 and 72 and arranged o be held in closed condition by respective latches 74 .nd 76 disposed on the outer ends of an upper closure wall member 78 secured on the upper ends of end wall nembers 40 and 42, as best seen in FIG. 3.

The end plate members 48 and 50 are circular in coniguration, providing cylindrical shoulder surfaces radilly disposed from the axis of the shaft 18. These shouler surfaces of the end plate members serve to support comminuting screen assembly commprised of a pair -f substantially identically sized screen elements 78 nd 80 which are arcuate in configuration with their dges supported by the shoulder surfaces of the end lates 48 and 50. Thus the screen elements 78 and 80 re ofa length sufficient to span the axial distance, seprating the end wali members 40 and 42 of the housing 4. The housing end walls 40, 42 and side walls 62, 64 efine a comminuting chamber containing the screen ssembly. The shaft [8 extends across this chamber and i rotatably supported at opposite ends of the chamber 1 the bearings l4, l6.

Overlying the screen elements 78 and 80 is a retainig assembly comprised of a pair of screen retaining \embers, arcuately configured and adapted to removbly secure the screen element in place on the end lates 48 and 50. The screen retaining members are 'ame-like arrangements pivotally secured at one end f each by a hinge means 82 which spans a distance lightly less than the extent of the span between the end late members 48 and 50. The other ends of each of the 'ame-like arrangements are provided with manually perable latch means depicted as push-pull type toggle lamps 84 and 86 which are well known latching elerents requiring no tedious or lengthy description.

The uppermost frame-like arrangement, designated enerally by the reference numeral 88, comprises arcu te frame elements 90 and 92 spaced apart by spacing lements 94 and by the clamp latching bar 96 and the ing: 82.

The lowermost frame-like arrangement, designated :nerally by the reference numeral 98, comprises arcute frame elements 100 and 102 spaced apart by spacig elements 104 and by the hinge 82.

it is now seen from the arrangement shown in FIGS.

and 4 that the screens 78 and 80 are snugged in place the frame-like retaining members 88 and 98 when i: clamps 84 and 86 are disposed as shown. When it desired to remove the screens 78 and 80 from the vill it is easily accomplished merely by unlatching as side wall members 62 and 64 at the latches 74 and 5 and allowing the members 62 and 64 to swing out 1 the hinges 70 and 72. Thereafter the toggle clamps I and 86 are unlatched to permit the screen retainers 3 and 98 to be swung open on the hinge 82, where- Jon the complete screen and retainer assembly may easily and quickly removed.

it is apparent, of course, that the comminuting screen lsembly could be comprised of three or more arcuate embers and screen elements, coupled by two or more hinge means, instead of the arrangement of two retainers and screens disclosed herein. The novel essence of the disclosure is that of readily removable assemblies, whether the assembly comes as a two-part, three-part assembly or more.

As is now apparent, the screen assembly envelopes a hammer assembly comprised of a plurality of hammer members 106 pivotally mounted, as by pivot pins 108, intermediate rotor plate members 110 secured on the shaft 18. The hammer assembly as shown is known from the prior art as an arrangement in which the hammer members are adapted to limited swinging movement on the rotor plates which carry the hammer members about the axis of the shaft when it is rotated. Thus the material to be comminuted, and which is fed into the space defined by the screen elements and the end plates through the passageways 44 and 46, is impacted by the hammer members against the screen elements to thereafter be reduced to fines which pass through the screen perforations to be exhausted through the outlet 60.

it is also apparent that further novelty resides in the removal of the limitation on the axial length of the hammer assembly imposed by the cantilevered arrangements of the prior art. Thus the screen assembly as disclosed not only permits rapid removal but also permits mill design with hammer assemblies of substantially greater axial length, hence substantially increased screen area, since the shaft can be supported by an outboard bearing, such as that shown at 14.

The inventor claims:

1. A hammer mill comprising:

a housing having an inlet for coarse material to be comminuted, an outlet for fine comminuted material and a comminuting chamber between said inlet and outlet bounded by spaced end walls and intervening side walls of said chamber,

coaxial bearings on said end walls,

a shaft extending across said chamber and rotatably supported at opposite ends of said chamber in said bearings,

a hammer assembly mounted on said shaft within said chamber for rotation with said shaft,

circular shoulders on the inner sides of said end walls in coaxial surrounding relation to said shaft,

a cylindrical comminuting screen assembly within said cornminuting chamber coaxially enclosing said hammer assembly and having open ends surrounding and disposed in seating contact with said shoulders, said screen assembly comprising two semicylindrical screen sections having adjacent axially extending edges. hinge means joining said screen sections along two adjacent edges thereof, and means releasably joining said screen sections along their other adjacent edges, whereby said screen sections may be hingably separated for removal and replacement about said hammer assembly,

said housing having passage means communicating said inlet to the interior of said screen assembly and a comminuting chamber space about said screen assembly communicating with said outlet, and

at least one side wall including a wall element which may be removed to provide access to said comminuting chamber for removal and replacement of said screen assembly.

2. A hammer mill according to claim 1 wherein:

said screen section joining means comprise toggle clamp means.

3. A hammer mill according to claim 1 wherein: A

hammer mill comprising:

a housing having an inlet for coarse material to be comminuted, an outlet for fine comminuted material and a comminuting chamber between said inlet and outlet bounded by spaced parallel end walls and intervening side walls of said chamber,

coaxial bearings on said end walls,

a shaft extending across said chamber and rotatably supported at opposite ends of said chamber in said bearings,

a hammer assembly mounted on said shaft within said chamber for rotation with said shaft,

circular shoulders on the inner sides of said end walls in coaxial surrounding relation to said shaft,

a cylindrical comminuting screen assembly within said comminuting chamber coaxially enclosing said hammer assembly and having open ends surrounding and disposed in seating contact with said shoulders,

said housing having passage means communicating said inlet to the interior of said screen assembly and a comminuting chamber space about said screen assembly communicating with said outlet,

said screen assembly including cylindrically curved screen sections which are separable laterally of said shaft for removal and replacement of the screen assembly and means releasably joining said screen sections,

each screen section comprising an arcuate frame including cylindrically curved frame members about said end plates, spacing elements extending between and joined to said frame elements, and a cylindrically curved screen about the inside of said frame, and

at least one side wall including a wall element which may be removed to provide access to said comminuting chamber for removal and replacement of said screen assembly.

4. A hammer mill according to claim 3 wherein:

said screen sections have adjacent axially extending edges, and

said screen section joining means comprise hinge means pivotally joining said screen sections along adjacent edges thereof and toggle clamp means releasably joining said screen sections along other adjacent edges thereof.

l i i 

1. A hammer mill comprising: a housing having an inlet for coarse material to be comminuted, an outlet for fine comminuted material and a comminuting chamber between said inlet and outlet bounded by spaced end walls and intervening side walls of said chamber, coaxial bearings on said end walls, a shaft extending across said chamber and rotatably supported at opposite ends of said chamber in said bearings, a hammer assembly mounted on said shaft within said chamber for rotation with said shaft, circular shoulders on the inner sides of said end walls in coaxial surrounding relation to said shaft, a cylindrical comminuting screen assembly within said comminuting chamber coaxially enclosing said hammer assembly and having open ends surrounding and disposed in seating contact with said shoulders, said screen assembly comprising two semi-cylindrical screen sections having adjacent axially extending edges, hinge means joining said screen sections along two adjacent edges thereof, and means releasably joining said screen sections along their other adjacent edges, whereby said screen sections may be hingably separated for removal and replacement about said hammer assembly, said housing having passage means communicating said inlet to the interior of said screen assembly and a comminuting chamber space about said screen assembly communicating with said outlet, and at least one side wall including a wall element which may be removed to provide access to said comminuting chamber for removal and replacement of said screen assembly.
 2. A hammer mill according to claim 1 wherein: said screen section joining means comprise toggle clamp means.
 3. A hammer mill according to claim 1 wherein: A hammer mill comprising: a housing having an inlet for coarse material to be comminuted, an outlet for fine comminuted material and a comminuting chamber between said inlet and outlet bounded by spaced parallel end walls and intervening side walls of said chamber, coaxial bearings on said end walls, a shaft extending across said chamber and rotatably supported at opposite ends of said chamber in said bearings, a hammer assembly mounted on said shaft within said chamber for rotation with said shaft, circular shoulders on the inner sides of said end walls in coaxial surrounding relation to said shaft, a cylindrical comminuting screen assembly within said comminuting chamber coaxially enclosing said hammer assembly and having open ends surrounding and disposed in seating contact with said shoulders, said housing having passage means communicating said inlet to the interior of said screen assembly and a comminuting chamber space about said screen assembly communicating with said outlet, said screen assembly including cylindrically curved screen sections which are separable laterally of said shaft for removal and replacement of the screen assembly and means releasably joining said screen sections, each screen section comprising an arcuate frame including cylindrically curved frame members about said end plates, spacing elements extending between and joined to said frame elements, and a cylindrically curved screen about the inside of said frame, and at least one side wall including a wall element which may be removed to provide access to said comminuting chamber for removal and replacement of said screen assembly.
 4. A hammer mill according to claim 3 wherein: said screen sections have adjacent axially extending edges, and said screen section joining means comprise hinge means pivotally joining said screen sections along adjacent edges thereof and toggle clamp means releasably joining said screen sections along other adjacent edges thereof. 